JP7167514B2 - pneumatic tire - Google Patents

Description

The present invention relates to pneumatic tires.

For example, Patent Document 1 discloses a pneumatic tire for trucks and buses, which is formed by arranging a plurality of block rows formed on a tread surface. In the pneumatic tire disclosed in Patent Document 1, the block width on the trailing side in the tire rotation direction is larger than the block width on the trailing side. Further, Patent Document 2 discloses a pneumatic tire in which blocks having vertical block edges extending in the tire circumferential direction are arranged. In the pneumatic tire disclosed in Patent Document 2, each vertical block edge is composed of a zigzag portion extending in a zigzag shape and a vertical projection projecting outward from the block from the zigzag portion.

JP-A-62-31503 JP 2017-30512 A

The pneumatic tires described in Patent Documents 1 and 2 have blocks arranged in parallel or in a zigzag pattern, but there is room for improvement in terms of improving performance on ice and snow and uneven wear resistance.

The present invention has been made in view of the above, and an object thereof is to provide a pneumatic tire capable of improving performance on ice and snow and uneven wear resistance.

In order to solve the above-described problems and achieve the object, a pneumatic tire according to one aspect of the present invention includes a plurality of circumferential main grooves formed on a tread surface and extending in the tire circumferential direction, and a plurality of circumferential main grooves formed on the tread surface. , a plurality of lug grooves extending in the tire width direction, a center land portion located between two circumferential main grooves arranged on both sides of the tire equator in the tire width direction with the tire equator interposed therebetween; a second land portion adjacent to the center land portion in the tire width direction, the center land portion being defined on both sides in the tire width direction by the two circumferential main grooves, and on both sides in the tire circumferential direction; It has a plurality of center blocks partitioned by two lug grooves, the second land portion has both sides in the tire width direction partitioned by the two circumferential main grooves, and both sides in the tire circumferential direction are partitioned by the two circumferential main grooves. It has a plurality of second blocks partitioned by the two lug grooves, and the center land portion includes a circumferential narrow groove extending in the tire circumferential direction and is divided in the tire width direction by the circumferential narrow groove. The plurality of center blocks are partitioned by, the circumferential narrow groove penetrates between the plurality of center blocks in the tire circumferential direction, and the second land portion is a circumferential narrow groove extending in the tire circumferential direction. The plurality of second blocks are partitioned by being divided in the tire width direction by the circumferential narrow grooves, and the center block has two oblique sides inclined in opposite directions to each other with respect to the tire circumferential direction. a connection point where one ends of each of the two oblique sides are connected to each other is arranged on one side of the tire equator in the tire width direction, and the other end of each of the two oblique sides is on the tire equator The two oblique sides of the center block are in contact with the circumferential narrow grooves of the center land portion, and the center block and the second block are disposed on the other side in the tire width direction. has a first circumferential edge portion and a second circumferential edge portion whose lengths in the tire width direction are different from each other, and the length in the tire width direction of the first circumferential edge portion is the length of the second circumferential edge portion. The center block and the second block, which are longer than the length of the direction edge portion in the tire width direction and are adjacent to each other in the tire width direction, are arranged at positions shifted in the tire circumferential direction.

The center block has a ratio of the length of the second circumferential edge portion in the width direction of the tire to the length of the first circumferential edge portion in the width direction of the tire of 0.75 or more and 0.95 or less. It is preferable that the ratio of the length of the first circumferential edge portion of the center block to the groove width of the circumferential main groove between the block and the second block is 150% or more and 300% or less.

In the second block, the ratio of the length of the first circumferential edge portion in the tire width direction to the length of the second circumferential edge portion in the tire width direction is 0.7 or more and 0.9 or less, and the center block It is preferable that a ratio of the length of the first circumferential edge portion of the second block to the groove width of the circumferential main groove between the second block and the second block is 150% or more and 300% or less.

The ratio Pb/Pa of the deviation amount Pb between the arrangement of the center blocks in the tire circumferential direction and the arrangement of the second blocks in the tire circumferential direction with respect to the length Pa of one pitch of the arrangement of the center blocks in the tire circumferential direction is 0. .4 or more and 0.5 or less.

In the center land portion, the plurality of center blocks are arranged side by side in the tire circumferential direction on both sides of the tire equator line, and the center blocks adjacent to each other in the tire width direction across the tire equator line are arranged. It is preferable that they are arranged at positions shifted in the tire circumferential direction.

It is preferable that the center blocks adjacent in the tire width direction across the tire equator line are arranged point-symmetrically with respect to a point on the tire equator line.

Two straight lines extending in the tire width direction passing through the ends of the second circumferential edge portions on the circumferential main groove side of the center blocks adjacent in the tire circumferential direction, and extending in the tire circumferential direction through the ends. It is preferable that the groove area ratio in the region partitioned by the two straight lines is 10% or more and 30% or less.

The angle α of the first circumferential edge portion of the center block with respect to the tire width direction is 0° or more and 20° or less, and the angle β of the second circumferential edge portion of the center block with respect to the tire width direction is 0. ° or more and 20° or less.

It is preferable that the difference between the angle α and the angle β is 5° or less.

In the center block, the end portion of the first circumferential edge portion on the side of the circumferential main groove and the end portion of the second circumferential edge portion on the side of the circumferential main groove are offset from each other in the tire width direction. and in the second block, the end portion of the first circumferential edge portion on the side of the circumferential main groove and the end portion of the second circumferential edge portion on the side of the circumferential main groove overlap the tire width They are preferably arranged offset from each other in the directions.

In the circumferential main groove between the center block and the second block, the ratio W2/W1 is 0.5 or more, where W1 is the maximum amplitude in the tire width direction and W2 is the groove width in the tire width direction. 0.8 or less.

In the circumferential main groove between the center block and the second block, the width of the groove in the tire width direction is set to W2, and the first circumferential edge portion of the center block on the side of the circumferential main groove The ratio W3/W2 is preferably 0.5 or more and 0.7 or less, where W3 is the distance between the first circumferential edge portion of the second block and the end portion on the circumferential main groove side.

A point P is the intersection of a straight line extending from the first circumferential edge portion of the center block and the second block, and a point is the end portion of the second circumferential edge portion of the second block on the side of the circumferential main groove. Q, the edge of the second block on the side of the circumferential main groove is formed along a straight line PQ connecting the point P and the point Q, and the angle of the straight line PQ with respect to the tire circumferential direction is ±5° or less. is preferably

A point R is the intersection of a straight line extending the first circumferential edge portion of the second block and the center block, and a point is the end portion of the second circumferential edge portion of the center block on the side of the circumferential main groove. S, the edge of the center block on the circumferential main groove side is formed along a straight line RS connecting the points R and S, and the angle of the straight line RS with respect to the tire circumferential direction is ±5° or less. is preferably

The circumferential main groove between the center block and the second block alternately has a plurality of circumferential sections extending along the tire circumferential direction and a plurality of inclined sections provided between the circumferential sections. The circumferential sections formed side by side in the tire circumferential direction and adjacent to each other across the inclined section are offset in the tire width direction. It is preferable that an angle of the inclined portion with respect to the tire circumferential direction is 30° or more and 50° or less.

A point R is the intersection of a straight line extending the first circumferential edge portion of the second block and the center block, and a point is the end portion of the second circumferential edge portion of the center block on the side of the circumferential main groove. S, the length in the tire circumferential direction of the line connecting the point S with the intersection of the straight line extending the straight line RS connecting the points R and S and the first circumferential edge portion of the center block. is LB, and the length from the point S to the inclined portion is LC, the ratio LC/LB is preferably 0.4 or more and 0.6 or less.

A point R is the intersection of a straight line extending the first circumferential edge portion of the second block and the center block, and a point is the end portion of the second circumferential edge portion of the center block on the side of the circumferential main groove. S, the length in the tire circumferential direction of the line connecting the point S with the intersection of the straight line extending the straight line RS connecting the points R and S and the first circumferential edge portion of the center block. A ratio LG/LB between LB and the tire circumferential length LG of the lug grooves between the center blocks adjacent in the tire circumferential direction is preferably 0.15 or more and 0.3 or less.

The groove depth of the lug grooves between the center blocks is 60% or more and 100% or less of the groove depth of the circumferential main grooves, and the groove depth of the lug grooves between the second blocks is , preferably 60% or more and 100% or less of the groove depth of the circumferential main groove.

The pneumatic tire according to the present invention can improve performance on ice and snow and uneven wear resistance.

FIG. 1 is a meridional cross-sectional view of a pneumatic tire according to this embodiment. FIG. 2 is a plan view showing the tread surface of the pneumatic tire according to this embodiment. FIG. 3 is an enlarged view showing a part of the center block row and the second block row in FIG. 4 is an enlarged view of a part of the center block row in FIG. 2. FIG. FIG. 5 is an enlarged view showing a part of the center block row and the second block row in FIG. 6 is an enlarged view of the circumferential main groove portion between the center block row and the second block row in FIG. 2. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Below, embodiments of the present invention will be described in detail based on the drawings. The embodiments are not intended to limit the present invention. In addition, the constituent elements of the embodiments include those that can be easily replaced by those skilled in the art, or those that are substantially the same. A plurality of modified examples described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art. Also, some components may not be used.

FIG. 1 is a meridional cross-sectional view of a pneumatic tire 1 according to this embodiment. FIG. 2 is a plan view showing the tread surface of the pneumatic tire 1 according to this embodiment.

In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side facing the rotation axis in the tire radial direction, or the tire radial direction outer side. means the side away from the rotating shaft in the tire radial direction. In addition, the tire circumferential direction refers to a circumferential direction around the rotation axis. In addition, the tire width direction refers to a direction parallel to the rotation axis, the tire width direction inner side refers to the side facing the tire equatorial plane (tire equator line) CL in the tire width direction, and the tire width direction outer side refers to the tire width direction. , the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane perpendicular to the rotation axis of the pneumatic tire 1 and passing through the center of the tire width of the pneumatic tire 1 . The tire width is the width in the tire width direction between portions positioned on the outside in the tire width direction, that is, the distance between the portions furthest from the tire equatorial plane CL in the tire width direction. A tire equator line is a line that is on the tire equatorial plane CL and extends along the tire circumferential direction of the pneumatic tire 1 . In this embodiment, the tire equatorial line is given the same symbol "CL" as the tire equatorial plane.

As shown in FIG. 1, the pneumatic tire 1 according to the present embodiment includes a tread portion 2, shoulder portions 3 on both outer sides in the tire width direction, and sidewall portions 4 and bead portions that are sequentially continuous from each shoulder portion 3. 5. Further, the pneumatic tire 1 includes a carcass layer 6 and a belt layer 7 .

The tread portion 2 is made of a rubber material (tread rubber), is exposed at the outermost portion of the pneumatic tire 1 in the tire radial direction, and its surface forms the contour of the pneumatic tire 1 . A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that comes into contact with the road surface during running. The tread surface 21 is provided with a plurality of (four in this embodiment) circumferential main grooves 22 extending in the tire circumferential direction. The tread surface 21 has a plurality of (in this embodiment, five) rib-shaped land portions 20ce, 20m1, 20m1, 20m1, 20m1, 20m1, 20m1, 20m1, 20m1, 20m1, 20m1, 20m1, 20m1, 20m1, 20m1, and 20m1. 20m2, 20s1, and 20s2 (hereinafter sometimes collectively referred to as land portion 20) are formed. The land portion 20 has circumferential narrow grooves 26 extending in the tire circumferential direction.

As shown in FIG. 2 , the tread surface 21 is provided with lug grooves 24 extending in a direction crossing the circumferential main grooves 22 extending in the tire circumferential direction in each land portion 20 . As a result, the land portion 20 is divided into a plurality of block rows 23ce, 23m1, 23m2, 23s1, and 23s2 in the tire circumferential direction by the lug grooves 24 (hereinafter sometimes collectively referred to as block row 23). is formed as Therefore, the land portion 20 has block rows 23 partitioned by circumferential grooves. In the block row 23, a plurality of blocks BB partitioned by a plurality of lug grooves 24 are arranged along the tire circumferential direction, and the block rows 23 are arranged side by side in the tire width direction. The block rows 23 are provided with circumferential narrow grooves 26 extending in the tire circumferential direction. The circumferential main groove 22 and the circumferential narrow grooves 26 are circumferential grooves extending in the tire circumferential direction. The circumferential narrow groove 26 penetrates between the blocks BB in the tire circumferential direction.

A main groove is a groove that has an obligation to display a wear indicator defined by JATMA. A lug groove is a lateral groove extending in the tire width direction, and functions as a groove by opening when the tire touches the ground. A sipe, which will be described later, is a notch formed in the tread surface and closed when the tire touches the ground.

The shoulder portions 3 are portions on both outer sides of the tread portion 2 in the tire width direction. Moreover, the sidewall portion 4 is exposed to the outermost side in the tire width direction of the pneumatic tire 1 . Moreover, the bead portion 5 has a bead core 51 and a bead filler 52 . The bead core 51 is formed by winding a bead wire, which is a steel wire, into a ring shape. The bead filler 52 is a rubber material arranged in a space formed by folding back the end portion of the carcass layer 6 in the width direction of the tire at the position of the bead core 51 toward the outside in the width direction of the tire.

Each of the carcass layers 6 is folded back from the inner side in the tire width direction to the outer side in the tire width direction with a pair of bead cores 51 at the ends thereof in the tire width direction, and is wound around in the tire circumferential direction in a toroidal shape to form the frame of the tire. is. The carcass layer 6 is formed by coating a plurality of carcass cords (not shown) arranged side by side with a certain angle in the tire circumferential direction along the tire meridian direction with respect to the tire circumferential direction. Carcass cords are made of steel or organic fibers (polyester, rayon, nylon, etc.).

The belt layer 7 has, for example, a multi-layered structure in which four layers of belts 71, 72, 73, and 74 are laminated, and is arranged outside the carcass layer 6 in the tire radial direction in the tread portion 2. It covers in the circumferential direction. The belts 71, 72, 73, and 74 are formed by coating a plurality of cords (not shown) arranged side by side at a predetermined angle with respect to the tire circumferential direction with a coat rubber. The cord is made of steel or organic fibers (polyester, rayon, nylon, etc.).

This pneumatic tire 1 is applied as a studless tire. Therefore, sipes may be provided on the surface of the land portion 20 that constitutes the tread surface 21 (not shown). By providing sipes on the surface of the land portion 20, performance on ice can be improved. The sipe may be an open sipe in which one end is open to the circumferential narrow groove 26 and the other end is open to the circumferential main groove 22, or both ends are open to either the circumferential narrow groove 26 or the circumferential main groove 22. It may be a closed sipe that does not open. A sipe is a groove with a width of less than 1 mm.

1 and 2, the block row located between the two circumferential main grooves 22 closest to the tire equator CL is called a center block row 23ce. The center block row 23ce is positioned in the center land portion 20ce between two circumferential main grooves 22 arranged on both sides of the tire equator CL in the tire width direction with the tire equator CL interposed therebetween. Further, block rows positioned between the circumferential main groove 22 closest to the tire ground-contact edge T and the tire ground-contact edge T are called shoulder block rows 23s1 and 23s2. The shoulder block rows 23s1 and 23s2 are located in the shoulder land portions 20s1 and 20s2. Intermediate block rows positioned between the center block row 23ce and the shoulder block rows 23s1 and 23s2 are called second block rows 23m1 and 23m2. The second block rows 23m1 and 23m2 are located in the second land portions 20m1 and 20m2 adjacent to the center land portion 20ce in the tire width direction. The distance between the tire contact edges T is the tread contact width.

The tread contact width is measured in the tire width direction when a pneumatic tire is mounted on a specified rim, filled with specified internal pressure, placed vertically on a flat surface, and a specified load is applied. refers to the maximum value of the ground contact width. The specified rim is a "standard rim" specified by JATMA, a "design rim" specified by TRA, or a "measuring rim" specified by ETRTO. The specified internal pressure is the maximum air pressure specified by JATMA, the maximum value specified by TRA "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", or the "INFLATION PRESSURES" specified by ETRTO. The specified load is the "maximum load capacity" defined by JATMA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "LOAD CAPACITY" defined by ETRTO.

As shown in FIG. 2 , the rib-shaped shoulder land portions 20 s 1 and 20 s 2 provided on the outermost side in the tire width direction have a plurality of lug grooves 29 and 30 . The lug grooves 29 and 30 have different groove widths. The lug grooves 29 and the lug grooves 30 are alternately arranged in the tire circumferential direction. That is, the shoulder land portions 20s1 and 20s2 include the first lug grooves 29 and the second lug grooves 30 having different groove widths, and the first lug grooves 29 and the second lug grooves 30 are alternately arranged in the tire. arranged in the circumferential direction. By arranging the lug grooves in the shoulder land portions 20s1 and 20s2 in this way, performance on ice and snow and uneven wear resistance performance can be improved.

The groove width is measured as the maximum value of the distance between the left and right groove walls at the opening of the groove in an unloaded state in which the tire is mounted on a specified rim and filled with a specified internal pressure. In a configuration in which the land portion 20 has a notch portion or a chamfered portion at the edge portion, the groove width is determined based on the intersection of the tread surface and the extension line of the groove wall in a cross-sectional view with the groove length direction as the normal direction. is measured. In addition, in a configuration in which the groove extends in a zigzag or wavy shape in the tire circumferential direction, the groove width is measured with reference to the center line of the amplitude of the groove wall. Groove depth is measured as the maximum distance from the tread surface to the groove bottom when the tire is mounted on a specified rim and filled with a specified internal pressure in an unloaded state. In addition, in a configuration in which the groove has partial irregularities or sipes at the groove bottom, the groove depth is measured excluding these.

Groove depth is measured as the maximum distance from the tread surface to the groove bottom when the tire is mounted on a specified rim and filled with a specified internal pressure in an unloaded state. In addition, in a configuration in which the groove has partial irregularities or sipes at the groove bottom, the groove depth is measured excluding these.

FIG. 3 is an enlarged view showing a part of the center block row 23ce and the second block row 23m2 in FIG. The center land portion 20ce has a center block row 23ce defined by two circumferential main grooves 22 on both sides in the tire width direction and by two lug grooves 24 on both sides in the tire circumferential direction. The center block row 23ce is composed of a plurality of center blocks B11, B12, B13, . . . The center blocks B11, B12, B13, . The length of the first circumferential edge portion EL1 in the tire width direction is longer than the length of the second circumferential edge portion ES1 in the tire width direction. That is, the first circumferential edge portion EL1 is long, and the second circumferential edge portion ES1 is short.

Assuming that the groove width of the circumferential main groove 22 between the center block row 23ce and the second block row 23m2 is W2, the length of the first circumferential edge portion EL1 in the tire width direction is 150% of the groove width W2. It is preferable that it is more than 300% or less. If the groove width W2 is within this range with respect to the length of the first circumferential edge portion EL1 in the tire width direction, performance on ice and snow and uneven wear resistance performance can be improved.

In the center blocks B11, B12, B13, . 0.75 or more and 0.95 or less. If the ratio LS/LL is less than 0.75, the performance on ice and snow is improved, but the uneven wear resistance performance is not sufficient. is not enough. If the ratio LS/LL is 0.75 or more and 0.95 or less, performance on ice and snow and uneven wear resistance performance can be improved.

Here, the length in the tire width direction of the first circumferential edge portion EL1 is the length in the tire width direction between the point Y and the point Y', which are both end portions of the first circumferential edge portion EL1. A point Y is an end portion of the first circumferential edge portion EL1 on the side of the circumferential main groove 22 . A point Y' is an end portion of the first circumferential edge portion EL1 on the circumferential narrow groove 26 side. Further, the length in the tire width direction of the second circumferential edge portion ES1 is the length in the tire width direction between the point S and the point S', which are both end portions of the second circumferential edge portion ES1. A point S is an end portion of the second circumferential edge portion ES1 on the side of the circumferential main groove 22 . A point S' is an end portion of the second circumferential edge portion ES1 on the circumferential narrow groove 26 side.

Notches and chamfers may be provided at the ends of the center blocks B11, B12, B13, . . . . In that case, the length in the tire width direction is measured assuming that no notches or chamfers are provided. In other words, except for the notch and chamfered portions, the groove wall is extended to draw a virtual line, and based on the virtual line, point Y, point Y', point S, and point S' are set, and the first circumference The length of the direction edge portion EL1 in the tire width direction and the length of the second circumferential edge portion ES1 in the tire width direction are measured. The same applies to point Y, point Y', point S, and point S' in the following description.

The second land portion 20m2 has a second block row 23m2 defined by two circumferential main grooves on both sides in the tire width direction and by two lug grooves 24 on both sides in the tire circumferential direction. The second block row 23m2 is composed of a plurality of second blocks B21, B22, B23, . Each of the second blocks B21, B22, B23, . The length of the first circumferential edge portion EL2 in the tire width direction is longer than the length of the second circumferential edge portion ES2 in the tire width direction. That is, the first circumferential edge portion EL2 is long, and the second circumferential edge portion ES2 is short.

Assuming that the groove width of the circumferential main groove 22 between the center block row 23ce and the second block row 23m2 is W2, the length of the first circumferential edge portion EL2 in the tire width direction is 150% of the groove width W2. It is preferable that it is more than 300% or less. If the groove width W2 is within this range with respect to the length in the tire width direction of the first circumferential edge portion EL2, performance on ice and snow and uneven wear resistance performance can be improved.

In the second blocks B21, B22, B23, . .7 or more and 0.9 or less. If the ratio LN/LM is less than 0.7, the performance on ice and snow is improved, but the uneven wear resistance performance is not sufficient. is not enough. If the ratio LN/LM is 0.7 or more and 0.9 or less, performance on ice and snow and uneven wear resistance performance can be improved.

Here, the length in the tire width direction of the first circumferential edge portion EL2 is the length in the tire width direction between the point X and the point X', which are both end portions of the first circumferential edge portion EL2. A point X is an end portion of the first circumferential edge portion EL2 on the side of the circumferential main groove 22 . A point X' is an end portion of the first circumferential edge portion EL2 on the circumferential narrow groove 26 side. Further, the length in the tire width direction of the second circumferential edge portion ES2 is the length in the tire width direction between the point Q and the point Q', which are both end portions of the second circumferential edge portion ES2. A point Q is an end portion of the second circumferential edge portion ES2 on the side of the circumferential main groove 22 . A point Q' is an end portion of the second circumferential edge portion ES2 on the circumferential narrow groove 26 side.

Notches and chamfers may be provided at the ends of the second blocks B21, B22, B23, . . . . In that case, the length in the tire width direction is measured assuming that no notches or chamfers are provided. That is, except for the notch and chamfered portions, the groove wall is extended to draw a virtual line, and based on the virtual line, point X, point X', point Q, and point Q' are set, and the first circumference The length of the directional edge portion EL2 in the tire width direction and the length of the second circumferential edge portion ES2 in the tire width direction are measured. The same applies to points X, X', Q, and Q' in the following description.

The center blocks B11, B12, B13, . . . and the second blocks B21, B22, B23, . For example, the center block B11 and the second block B21 that are adjacent in the tire width direction are arranged at positions shifted in the tire circumferential direction. The center block B12 and the second block B21, which are adjacent in the tire width direction, are arranged at positions shifted in the tire circumferential direction. The center block B12 and the second block B22, which are adjacent in the tire width direction, are arranged at positions shifted in the tire circumferential direction. The center block B13 and the second block B22, which are adjacent in the tire width direction, are arranged at positions shifted in the tire circumferential direction. The center block B13 and the second block B23, which are adjacent in the tire width direction, are arranged at positions shifted in the tire circumferential direction.

Here, the arrangement of the center blocks B11, B12, B13, . The ratio Pb/Pa of the displacement amount Pb from the arrangement in the tire circumferential direction is preferably 0.4 or more and 0.5 or less. If the ratio Pb/Pa is less than 0.4, performance on ice and snow and uneven wear resistance cannot be improved.

In this way, the center blocks B11, B12, B13, . . . and the second blocks B21, B22, B23, . That is, the center blocks B11, B12, B13, . . . and the second blocks B21, B22, B23, .

Since the center blocks B11, B12, B13, . . . and the second blocks B21, B22, B23, . , B22, B23, . . . are arranged in a staggered manner in the tire circumferential direction. By arranging the first circumferential edge portion EL1 and the first circumferential edge portion EL2 in a staggered manner in the tire circumferential direction, performance on ice and snow and uneven wear resistance performance can be improved.

Center blocks B11, B12, B13, . . . and second blocks B21, B22, B23, . By arranging sipes on the surface of each block, performance on ice and snow can be further improved.

The center blocks B11, B12, B13, . . . and the second blocks B21, B22, B23, . The inclined portion 120 is a portion that is inclined with respect to the tire circumferential direction and with respect to the tire width direction at the end portion of each block on the side of the circumferential main groove 22 .

FIG. 4 is an enlarged view of part of the center block row 23ce in FIG. The center land portion 20ce is divided into center blocks B11, B12, . . . and center blocks B11', B12', . Therefore, a plurality of center blocks B11, B12 . . . and a plurality of center blocks B11', B12' . The groove width of the circumferential narrow grooves 26 is preferably 1 mm or more and 5 mm or less.

Center blocks B11, B12, . . . and center blocks B11′, B12′, . For example, the center blocks B11 and B11' adjacent to each other in the tire width direction are arranged at positions shifted in the tire circumferential direction. The center block B11' and the center block B12, which are adjacent in the tire width direction, are arranged at positions shifted in the tire circumferential direction. The center block B12 and the center block B12' adjacent in the tire width direction are arranged at positions shifted in the tire circumferential direction. Therefore, the plurality of center blocks B11, B12, . . . and the plurality of center blocks B11′, B12′, . . By forming the center block row 23ce into two block rows and arranging the two block rows in a zigzag pattern, uneven wear resistance performance is further improved.

Also, the center blocks adjacent in the tire width direction across the tire equator line CL are arranged point-symmetrically with respect to a point on the tire equator line CL. For example, they are arranged symmetrically with respect to the point N in FIG. A point N in FIG. 2 is an intersection point between the center line of the groove width of the circumferential narrow groove 26 and the equator line CL. By adopting a point-symmetrical pattern, two block rows are arranged in a zigzag pattern regardless of the mounting position of the pneumatic tire 1 on the vehicle, improving uneven wear resistance.

Here, the area 10 is defined in the center block row 23ce. The region 10 includes two straight lines LW1 and LW2 that extend in the tire width direction and pass through points S at the ends of the second circumferential edge portions ES1 on the circumferential main groove side of the center blocks that are adjacent in the tire circumferential direction. This is an area defined by two straight lines LC1 and LC2 extending in the tire circumferential direction passing through the end point S. At this time, the groove area ratio in region 10 is preferably 10% or more and 30% or less. The groove area ratio is the ratio of the groove area within region 10 to the contact area of region 10 . That is, groove area/ground contact area×100%. In this embodiment, groove area does not include sipe openings. If the groove area ratio is less than 10%, the uneven wear resistance is improved, but the performance on ice and snow is not sufficient. On the other hand, if the groove area ratio is more than 30%, the performance on ice and snow is improved, but the uneven wear resistance performance is not sufficient. If the groove area ratio in region 10 is 10% or more and 30% or less, performance on ice and snow and uneven wear resistance performance can be improved. It should be noted that the groove area ratio in region 10 is more preferably 17% or more and 25% or less.

In FIG. 4, the angle α of the first circumferential edge portion EL1 of the center block row 23ce with respect to the tire width direction is 0° or more and 20° or less, and the second circumferential edge portion ES1 of the center block row 23ce The angle β with respect to the width direction is preferably 0° or more and 20° or less. The angles α and β are substantially the same, and preferably the difference between the angles α and β is 5° or less. If the angle α and the angle β are within such ranges, the uneven wear resistance performance and performance on ice and snow are further improved.

FIG. 5 is an enlarged view showing a part of the center block row 23ce and the second block row 23m2 in FIG. As shown in FIG. 5, in the center blocks B11, B12, B13, . The point S at the end of the portion ES1 on the side of the circumferential main groove 22 is offset from each other in the tire width direction. The distance along the tire width direction between the end point Y and the end point S is defined as an offset amount Ga. A ratio Ga/W2 of the offset amount Ga to the groove width W2 of the circumferential main groove 22 is preferably 0.3 or more and 0.5 or less. By arranging the first circumferential edge portion EL1 and the second circumferential edge portion ES1 to be offset on the circumferential main groove 22 side, edge components are increased, and performance on ice and snow can be further improved. If the ratio Ga/W2 is less than 0.3, the performance on ice and snow is improved, but the uneven wear resistance performance is not sufficient. not enough. If the ratio Ga/W2 is 0.3 or more and 0.5 or less, performance on ice and snow and uneven wear resistance performance can be improved.

Further, as shown in FIG. 5, in the second blocks B21, B22, B23, . The point Q at the end of the direction edge portion ES2 on the side of the circumferential main groove 22 is offset from each other in the tire width direction. The distance along the tire width direction between the end point X and the end point Q is defined as an offset amount Gb. A ratio Gb/W2 of the offset amount Gb to the groove width W2 of the circumferential main groove 22 is preferably 0.3 or more and 0.5 or less. By arranging the first circumferential edge portion EL2 and the second circumferential edge portion ES2 to be offset on the circumferential main groove 22 side, edge components are increased, and performance on ice and snow can be further improved. If the ratio Gb/W2 is less than 0.3, the performance on ice and snow is improved, but the uneven wear resistance performance is not sufficient. not enough. If the ratio Gb/W2 is 0.3 or more and 0.5 or less, performance on ice and snow and uneven wear resistance performance can be improved.

Here, in FIG. 5, the maximum amplitude in the tire width direction of the circumferential main grooves 22 between the center blocks B11, B12, B13, . . . and the second blocks B21, B22, B23 . be W2. The maximum amplitude W1 is the distance in the tire width direction between the outermost sides of the amplitude of the circumferential main grooves 22 in the tire width direction. At this time, the ratio W2/W1 of the groove width W2 to the maximum amplitude W1 is preferably 0.5 or more and 0.8 or less. If the ratio W2/W1 is less than 0.5, the performance on ice and snow is improved, but the uneven wear resistance performance is not sufficient. not enough. If the ratio W2/W1 is 0.5 or more and 0.8 or less, performance on ice and snow and uneven wear resistance performance can be improved.

5, the width of the circumferential main groove 22 between the center blocks B11, B12, B13, . . . and the second blocks B21, B22, B23, . A point Y at the end of the first circumferential edge portion EL1 of the second blocks B21, B22, B23, . When the distance in the tire width direction from the point X is W3, the ratio W3/W2 is preferably 0.5 or more and 0.7 or less. If the ratio W3/W2 is less than 0.5, the performance on ice and snow is improved, but the uneven wear resistance performance is not sufficient. not enough. If the ratio W3/W2 is 0.5 or more and 0.7 or less, performance on ice and snow and uneven wear resistance performance can be improved.

In FIG. 5, a point P is the intersection of a straight line extending the first circumferential edge portion EL1 of the center blocks B11, B12, B13, . . . For example, a point P is the intersection of a straight line LL2 extending from the first circumferential edge portion EL1 of the center block B13 and the second block B22. A point Q is an end portion of the second circumferential edge portion ES2 of the second block B22 on the side of the circumferential main groove 22 . At this time, the edge of the second block B22 on the side of the circumferential main groove 22 is formed along the straight line PQ connecting the point P and the point Q, and the angle θPQ of the straight line _PQ with respect to the tire circumferential direction is ±5° or less. is preferred. That the angle θ _PQ is ±5° or less means that the straight line PQ is substantially parallel to the tire circumferential direction. When the tire circumferential direction and the straight line PQ are parallel, the angle θ _PQ is 0°.

Since the edge of the second block B22 on the side of the circumferential main groove 22 is formed along the straight line PQ, the groove volume at the intersection of the circumferential main groove 22 and the lug groove 24 located in the center region where the ground contact pressure is high is large. It becomes possible to increase the shear force in snow, and the performance on ice and snow is further improved.

In FIG. 5, a point R is the intersection of a straight line extending the first circumferential edge portion EL2 of the second blocks B21, B22, B23, . . . For example, a point R is the intersection of a straight line extending the first circumferential edge portion EL2 of the second block B22 and the center block B12. Further, a point S is the end portion of the second circumferential edge portion ES1 of the center block B12 on the side of the circumferential main groove 22 . At this time, the edge of the center block B12 on the side of the circumferential main groove 22 is formed along the straight line RS connecting the points R and S, and the angle θ _RS of the straight line RS with respect to the tire circumferential direction is ±5° or less. is preferred. That the angle θ _RS is ±5° or less means that the straight line RS is substantially parallel to the tire circumferential direction. When the tire circumferential direction and the straight line RS are parallel, the angle θ _RS is 0°.

Since the edge of the center block B12 on the side of the circumferential main groove 22 is formed along the straight line RS, the groove volume at the intersection of the circumferential main groove 22 and the lug groove 24 located in the center region where the ground contact pressure is high is large. It becomes possible to increase the shear force in snow, and the performance on ice and snow is further improved.

FIG. 6 is an enlarged view of the portion of the circumferential main groove 22 between the center block row 23ce and the second block row 23m2 in FIG. 6, the circumferential main grooves 22 between the center blocks B11, B12, B13, . . . and the second blocks B21, B22, B23, . and a plurality of inclined sections 12 provided therebetween. The circumferential main groove 22 is formed by alternately lining up a plurality of circumferential sections 11 and a plurality of inclined sections 12 in the tire circumferential direction.

The circumferential sections 11 that are adjacent to each other with the inclined section 12 interposed therebetween are not constant in position in the tire width direction, but are offset in the tire width direction. In the example of FIG. 6, the tire width direction of the circumferential section 11 including the end point X is closer to the equator line CL than the position of the circumferential section 11 including the end point Y in the tire width direction. , and the circumferential sections 11 are offset in the tire width direction. In this manner, the circumferential sections 11 are offset in the tire width direction. The tire width direction offset amount 110 between the circumferential sections 11 is preferably 30% or more and 50% or less of the groove width W2 of the circumferential main groove 22 . If the offset amount 110 with respect to the groove width W2 is less than 30%, the uneven wear resistance performance is improved, but the performance on ice and snow is not sufficient. If the offset amount 110 with respect to the groove width W2 is more than 50%, the performance on ice and snow improves, but the uneven wear resistance performance is not sufficient. When the offset amount 110 with respect to the groove width W2 is 30% or more and 50% or less, it is possible to further improve uneven wear resistance performance and performance on ice and snow.

The inclined section 12 includes inclined portions 120 which are part of the ends of the center blocks B11, B12, B13, . . . or the second blocks B21, B22, B23, . It is preferable that the angle θ of the portion 120 is 30° or more and 50° or less. If the angle θ of the inclined portion 120 is less than 30°, the first circumferential edge portions EL1 and EL2 are shortened and the uneven wear resistance performance is improved, but the performance on ice and snow is not sufficient. If the angle θ of the inclined portion 120 is greater than 50°, the first circumferential edge portions EL1 and EL2 are lengthened and the performance on ice and snow is improved, but the uneven wear resistance is not sufficient. If the angle θ is 30° or more and 50° or less, the uneven wear resistance performance and performance on ice and snow can be further improved.

Returning to FIG. 5, the intersection of the straight line LL1 extending the first circumferential edge portion EL2 of the second block B23 and the center block B13 is defined as a point R, and the circumferential main groove 22 of the second circumferential edge portion ES1 of the center block B13 Let point S be the end of the side. Let LB be the length in the tire circumferential direction of the line connecting the point S and the intersection U between the straight line L22, which is an extension of the straight line RS connecting the points R and S, and the first circumferential edge portion EL1 of the center block B13, and the point S A ratio LC/LB of the length LC to the length LB is preferably 0.4 or more and 0.6 or less.

When the ratio LC/LB is less than 0.4, performance on ice and snow is improved, but uneven wear resistance is not sufficient. If the ratio LC/LB is greater than 0.6, the uneven wear resistance performance is improved, but the performance on ice and snow is not sufficient. If the ratio LC/LB is 0.4 or more and 0.6 or less, uneven wear resistance performance and performance on ice and snow can be further improved.

In FIG. 5, a straight line LL1 extending the first circumferential edge portion EL2 of the second blocks B21, B22, B23, . . . and the center blocks B11, B12, B13, . A point S is the end of the second circumferential edge portion ES1 on the side of the circumferential main groove 22 . At this time, the length LB in the tire circumferential direction of the line connecting the point S and the intersection point U between the straight line L22, which is an extension of the straight line RS connecting the points R and S, and the center block, and the distance between the center blocks adjacent in the tire circumferential direction. The ratio LG/LB to the tire circumferential direction length LG of the lug grooves 24 between is preferably 0.15 or more and 0.3 or less. The tire circumferential length LG is the maximum groove width in the tire circumferential direction.

If the ratio LG/LB is less than 0.15, the uneven wear resistance performance is improved, but the performance on ice and snow is not sufficient. If the ratio LG/LB is greater than 0.3, performance on ice and snow is improved, but uneven wear resistance is not sufficient. If the ratio LG/LB is 0.15 or more and 0.3 or less, performance on ice and snow and uneven wear resistance performance can be improved. The ratio LG/LB is more preferably 0.2 or more and 0.25 or less.

5, the groove depth of the lug grooves 24 between the center blocks B11, B12, B13, . Moreover, the groove depth of the lug grooves 24 between the second blocks B21, B22, B23, . .

If the groove depth of the lug grooves 24 is less than 60% of the groove depth of the circumferential main grooves 22, the uneven wear resistance performance is improved, but the performance on ice and snow is not sufficient. If the groove depth of the lug grooves 24 is greater than 100% of the groove depth of the circumferential main grooves 22, the performance on ice and snow is improved, but the uneven wear resistance is not sufficient. If the groove depth of the lug grooves 24 is 60% or more and 100% or less of the groove depth of the circumferential main grooves 22, performance on ice and snow and uneven wear resistance performance can be improved.

(summary)
By arranging the long edge portions of the center block and the long edge portions of the second blocks in a staggered manner in the tire circumferential direction, performance on ice and snow and uneven wear resistance performance can be improved.

In this example, a plurality of types of pneumatic tires under different conditions were subjected to performance tests regarding performance on ice and snow and resistance to uneven wear on a test course (see Tables 1 to 3). In all cases, pneumatic tires with four main grooves were used.

In this performance test, heavy-duty pneumatic tires with a tire size of 275/80R22.5 were mounted on specified rims, filled with specified internal pressure, and tested on a 2-D4 (2 front wheels - 4 rear drive wheels) test vehicle. attached to the

In the performance test of performance on ice and snow, a feeling evaluation was performed by a test driver when the test vehicle was driven on a test course having an icy road surface and a snowy road surface. The feeling evaluation was indexed using a pneumatic tire of a conventional example described later as a standard (100). The larger the index value, the higher the steering stability on icy and snowy road surfaces and the better the performance on ice and snow.

As for the uneven wear resistance performance, a rim on which the pneumatic tire 1 was mounted was attached to the drive shaft of the above vehicle, and the amount of heel and toe wear after running 20,000 km was measured by a market monitor. The measurement results were indexed using the conventional pneumatic tire as a reference (100). A larger index value indicates better performance.

In Table 1, the tire of the conventional example is a tire in which square blocks are arranged in a zigzag pattern.

In Table 1, the tire of Comparative Example 1 is, for example, a pneumatic tire having a block with a block width on the trailing side larger than that on the trailing side in the tire rotation direction, as in Patent Document 1.

In Table 1, the tire of Comparative Example 2 is composed of a zigzag portion extending in a zigzag shape from the edge of the vertical block and a vertical convex portion projecting outward from the block, as in Patent Document 2, for example. It is a pneumatic tire with blocks arranged.

Referring to Examples 1 to 33 in Tables 1 to 3, the center block and the second block have a first circumferential edge portion and a second circumferential edge portion having different lengths in the tire width direction at both ends in the tire circumferential direction. The length of the first circumferential edge portion in the tire width direction is longer than the length of the second circumferential edge portion in the tire width direction, and the center blocks adjacent to each other in the tire width direction. It can be seen that good results are obtained when the second blocks are arranged at positions shifted in the tire circumferential direction, that is, when they are arranged in a zigzag arrangement.

Further, regarding the center block, the ratio of the length of the second circumferential edge portion to the length of the first circumferential edge portion is 0.75 or more and 0.95 or less, and the circumference between the center block and the second block is When the ratio of the length of the first circumferential edge portion of the center block to the groove width of the directional main groove is 150% or more and 300% or less, for the second block, the length of the first circumferential edge portion and the second circumferential direction The ratio to the length of the edge portion is 0.7 or more and 0.9 or less, and the ratio of the length of the first circumferential edge portion of the second block to the groove width of the circumferential main groove between the center block and the second block is 150% or more and 300% or less, good results can be obtained.

The ratio Pb/Pa of the shift amount Pb between the arrangement of the center blocks in the tire circumferential direction and the arrangement of the second blocks in the tire circumferential direction with respect to the length Pa of one pitch of the arrangement of the center blocks in the tire circumferential direction is 0.4 or more and 0. It can be seen that good results are obtained when the value is 0.5 or less.

In the center land portion, a plurality of center blocks are arranged side by side in the tire circumferential direction on both sides of the tire equator line, and the center blocks adjacent in the tire width direction across the tire equator line are displaced in the tire circumferential direction. It can be seen that good results can be obtained when they are arranged in a staggered position.

When the groove area ratio in region 10 is 10% or more and 30% or less, the angle α of the first circumferential edge portion of the center block with respect to the tire width direction is 0° or more and 20° or less, and It can be seen that good results are obtained when the angle β of the circumferential edge portion with respect to the tire width direction is 0° or more and 20° or less, and when the difference between the angle α and the angle β is 5° or less.

In the center block, an end portion of the first circumferential edge portion on the circumferential main groove side and an end portion of the second circumferential edge portion on the circumferential main groove side are arranged offset from each other in the tire width direction, and In the second block, the end portion of the first circumferential edge portion on the side of the circumferential main groove and the end portion of the second circumferential direction edge portion on the side of the circumferential main groove are offset from each other in the tire width direction. It can be seen that good results are obtained when

In the circumferential main groove between the center block and the second block, when the maximum amplitude in the tire width direction is W1 and the groove width in the tire width direction is W2, the ratio W2/W1 is 0.5 or more and 0.8 or less. It can be seen that good results are obtained when

In the circumferential main groove between the center block and the second block, the groove width in the tire width direction is W2, and the end of the first circumferential edge portion of the center block on the side of the circumferential main groove and the first circumferential groove of the second block It can be seen that good results are obtained when the ratio W3/W2 is 0.5 or more and 0.7 or less, where W3 is the distance between the direction edge portion and the end portion on the side of the circumferential main groove.

When the intersection of the straight line extending the first circumferential edge of the center block and the second block is point P, and the end of the second circumferential edge of the second block on the main groove side in the circumferential direction is point Q, the second Good results are obtained when the edge of the block on the circumferential direction main groove side is formed along a straight line PQ connecting point P and point Q, and the angle of straight line PQ with respect to the tire circumferential direction is ±5° or less. I understand.

When the intersection of the straight line extending the first circumferential edge of the second block and the center block is point R, and the end of the second circumferential edge of the center block on the side of the main groove in the circumferential direction is point S, the center Good results are obtained when the edge of the block on the side of the circumferential main groove is formed along a straight line RS connecting point R and point S, and the angle of straight line RS with respect to the tire circumferential direction is ±5° or less. I understand.

The circumferential main groove between the center block and the second block has a plurality of circumferential sections extending along the tire circumferential direction and a plurality of inclined sections provided between the circumferential sections alternately in the tire circumferential direction. Circumferential sections formed side by side and adjacent to each other across an inclined section are offset in the tire width direction, and the inclined section is a part of the end of the center block or the second block on the side of the circumferential main groove. It can be seen that good results are obtained when the angle of the inclined portion with respect to the tire circumferential direction is 30° or more and 50° or less.

When the intersection of the straight line extending the first circumferential edge of the second block and the center block is point R, and the end of the second circumferential edge of the center block on the circumferential main groove side is point S, point Let LB be the length in the tire circumferential direction of the line connecting the point S and the intersection of the straight line extending the straight line RS connecting R and point S with the first circumferential edge portion of the center block, and from the point S to the inclined portion. It can be seen that good results are obtained when the ratio LC/LB is 0.4 or more and 0.6 or less, where LC is the length of .

When the intersection of the straight line extending the first circumferential edge of the second block and the center block is point R, and the end of the second circumferential edge of the center block on the circumferential main groove side is point S, point The length LB in the tire circumferential direction of the line connecting the point S with the intersection of the straight line extended from the straight line RS connecting R and point S with the center block, and the length of the lug groove between the center blocks adjacent in the tire circumferential direction. It can be seen that good results are obtained when the ratio LG/LB to the tire circumferential direction length LG is 0.15 or more and 0.3 or less.

The groove depth of the lug grooves between the center blocks is 60% or more and 100% or less of the groove depth of the circumferential main grooves, and the groove depth of the lug grooves between the second blocks is equal to the circumferential main grooves. It can be seen that good results can be obtained when the groove depth is 60% or more and 100% or less of the groove depth.

1 pneumatic tire 2 tread portion 3 shoulder portion 4 sidewall portion 5 bead portion 6 carcass layer 7 belt layer 10 region 11 circumferential section 12 inclined section 20 land portion 20ce center land portion 20m1, 20m2 second land portion 20s1, 20s2 shoulder land Part 21 Tread surface 22 Circumferential main groove 23ce Center block rows 23m1, 23m2 Second block rows 23s1, 23s2 Shoulder block rows 24, 29, 30 Lug groove 26 Circumferential narrow groove 51 Bead core 52 Bead filler 71, 72, 73, 74 Belt 120 Inclined portion B11, B12, B13 Center block B21, B22, B23 Second block BB Block CL Tire equator line (tire equatorial plane)
EL1, EL2 First circumferential edge portions ES1, ES2 Second circumferential edge portions

Claims (18)

A plurality of circumferential main grooves formed on the tread surface and extending in the tire circumferential direction, a plurality of lug grooves formed on the tread surface and extending in the tire width direction, and the tire equator in the tire width direction across the tire equator line A center land portion located between two circumferential main grooves arranged on both sides of a line, and a second land portion adjacent to the center land portion in the tire width direction,
The center land portion has a plurality of center blocks defined by the two circumferential main grooves on both sides in the tire width direction and by the two lug grooves on both sides in the tire circumferential direction,
The second land portion has a plurality of second blocks defined by the two circumferential main grooves on both sides in the tire width direction and by the two lug grooves on both sides in the tire circumferential direction,
The center land portion includes circumferential narrow grooves extending in the tire circumferential direction, and is divided in the tire width direction by the circumferential narrow grooves to partition the plurality of center blocks. penetrates between the plurality of center blocks in the tire circumferential direction,
The second land portion includes a circumferential narrow groove extending in the tire circumferential direction, and is divided in the tire width direction by the circumferential narrow groove to partition the plurality of second blocks,
The center block has two oblique sides that are slanted in opposite directions with respect to the tire circumferential direction,
A connection point where one ends of the two oblique sides are connected to each other is arranged on one side of the tire equator line in the tire width direction,
The other ends of the two oblique sides are arranged on the other side of the tire equator in the tire width direction,
The two oblique sides of the center block are in contact with the circumferential narrow grooves of the center land portion,
The center block and the second block each have a first circumferential edge portion and a second circumferential edge portion having different lengths in the tire width direction at both ends in the tire circumferential direction,
The length of the first circumferential edge portion in the tire width direction is longer than the length of the second circumferential edge portion in the tire width direction,
A pneumatic tire in which the center block and the second block adjacent in the tire width direction are arranged at positions shifted in the tire circumferential direction. The center block has a ratio of the length of the second circumferential edge portion in the width direction of the tire to the length of the first circumferential edge portion in the width direction of the tire of 0.75 or more and 0.95 or less. 2. The air according to claim 1, wherein a ratio of the length of the first circumferential edge portion of the center block to the groove width of the circumferential main groove between the block and the second block is 150% or more and 300% or less. entered tire. In the second block, the ratio of the length of the first circumferential edge portion in the tire width direction to the length of the second circumferential edge portion in the tire width direction is 0.7 or more and 0.9 or less, and the center block 3. The ratio of the length of the first circumferential edge portion of the second block to the groove width of the circumferential main groove between the second block and the second block is 150% or more and 300% or less. pneumatic tires. The ratio Pb/Pa of the deviation amount Pb between the arrangement of the center blocks in the tire circumferential direction and the arrangement of the second blocks in the tire circumferential direction with respect to the length Pa of one pitch of the arrangement of the center blocks in the tire circumferential direction is 0. 4 or more and 0.5 or less, the pneumatic tire according to any one of claims 1 to 3. In the center land portion, the plurality of center blocks are arranged side by side in the tire circumferential direction on both sides of the tire equator line, and the center blocks adjacent to each other in the tire width direction across the tire equator line are arranged. The pneumatic tire according to any one of claims 1 to 4, which is arranged at a position shifted in the tire circumferential direction. The air according to any one of claims 1 to 5, wherein the center blocks adjacent in the tire width direction across the tire equator line are arranged point-symmetrically with respect to a point on the tire equator line. entered tire. Two straight lines extending in the tire width direction passing through the ends of the second circumferential edge portions on the circumferential main groove side of the center blocks adjacent in the tire circumferential direction, and extending in the tire circumferential direction through the ends. The pneumatic tire according to any one of claims 1 to 6, wherein the groove area ratio in the region defined by the two straight lines is 10% or more and 30% or less. The angle α of the first circumferential edge portion of the center block with respect to the tire width direction is 0° or more and 20° or less, and the angle β of the second circumferential edge portion of the center block with respect to the tire width direction is 0. 8. The pneumatic tire according to any one of claims 1 to 7, wherein the angle is 20° or more. The pneumatic tire according to claim 8, wherein the difference between the angle α and the angle β is 5° or less. In the center block, the end portion of the first circumferential edge portion on the side of the circumferential main groove and the end portion of the second circumferential edge portion on the side of the circumferential main groove are offset from each other in the tire width direction. and in the second block, the end portion of the first circumferential edge portion on the side of the circumferential main groove and the end portion of the second circumferential edge portion on the side of the circumferential main groove overlap the tire width 10. A pneumatic tire according to any one of claims 1 to 9, arranged in directions offset from each other. In the circumferential main groove between the center block and the second block,
A ratio W2/W1 of 0.5 or more and 0.8 or less, wherein W1 is the maximum amplitude in the tire width direction and W2 is the groove width in the tire width direction. Pneumatic tires as described. In the circumferential main groove between the center block and the second block,
The groove width in the tire width direction is W2, and the end portion of the first circumferential edge portion of the center block on the side of the circumferential main groove and the first circumferential edge portion of the second block on the side of the circumferential main groove. 12. The pneumatic tire according to any one of claims 1 to 11, wherein the ratio W3/W2 is 0.5 or more and 0.7 or less, where W3 is the distance from the end of the tire. A point P is the intersection of a straight line extending from the first circumferential edge portion of the center block and the second block, and a point is the end portion of the second circumferential edge portion of the second block on the side of the circumferential main groove. Q, the edge of the second block on the side of the circumferential main groove is formed along a straight line PQ connecting the point P and the point Q, and the angle of the straight line PQ with respect to the tire circumferential direction is ±5° or less. The pneumatic tire according to any one of claims 1 to 12. A point R is the intersection of a straight line extending the first circumferential edge portion of the second block and the center block, and a point is the end portion of the second circumferential edge portion of the center block on the side of the circumferential main groove. S, the edge of the center block on the circumferential main groove side is formed along a straight line RS connecting the points R and S, and the angle of the straight line RS with respect to the tire circumferential direction is ±5° or less. The pneumatic tire according to any one of claims 1 to 13. The circumferential main groove between the center block and the second block alternately has a plurality of circumferential sections extending along the tire circumferential direction and a plurality of inclined sections provided between the circumferential sections. Formed side by side in the tire circumferential direction,
The circumferential sections adjacent to each other across the inclined section are offset in the tire width direction, and the inclined section is a part of the end of the center block or the second block on the side of the circumferential main groove. 15. The pneumatic tire according to any one of claims 1 to 14, comprising a certain inclined portion, wherein the angle of said inclined portion with respect to the tire circumferential direction is 30[deg.] or more and 50[deg.] or less. A point R is the intersection of a straight line extending the first circumferential edge portion of the second block and the center block, and a point is the end portion of the second circumferential edge portion of the center block on the side of the circumferential main groove. S, the length in the tire circumferential direction of the line connecting the point S with the intersection of the straight line extending the straight line RS connecting the points R and S and the first circumferential edge portion of the center block. 16. The pneumatic tire according to claim 15, wherein the ratio LC/LB is 0.4 or more and 0.6 or less, where LB is the length from the point S to the inclined portion LC. A point R is the intersection of a straight line extending the first circumferential edge portion of the second block and the center block, and a point is the end portion of the second circumferential edge portion of the center block on the side of the circumferential main groove. S, the length in the tire circumferential direction of the line connecting the point S with the intersection of the straight line extending the straight line RS connecting the points R and S and the first circumferential edge portion of the center block. 17. A ratio LG/LB between LB and the tire circumferential length LG of the lug groove between the center blocks adjacent in the tire circumferential direction is 0.15 or more and 0.3 or less. A pneumatic tire according to any one of the preceding claims. The groove depth of the lug grooves between the center blocks is 60% or more and 100% or less of the groove depth of the circumferential main grooves,
18. The air according to any one of claims 1 to 17, wherein the groove depth of the lug grooves between the second blocks is 60% or more and 100% or less of the groove depth of the circumferential main grooves. entered tire.

Images